SCSNSCSN http://www.scsn.org Southern California Seismic Network Tue, 16 Jul 2019 18:16:11 +0000 en-US hourly 1 https://wordpress.org/?v=5.1.1 07/2019, Ridgecrest Sequence: M6.4 and M7.1 ../../index.php/2019/07/04/07-2019-ridgecrest-sequence/ ../../index.php/2019/07/04/07-2019-ridgecrest-sequence/#respond Thu, 04 Jul 2019 18:09:16 +0000 http://www.scsn.org/?p=3469 ]]> Please note that this sequence has been renamed, earlier reports used ‘Searles Valley Sequence’.

The Ridgecrest Sequence started on July 4th, 2019 and so far has included one strong (M6.4, 2019/07/04) and one major (M7.1 2019/07/05) earthquake. The closest large population center is the city of Ridgecrest with a population of 28k people. Maximum shaking levels are estimated to be MMI IX (Violent) in the epicentral region and very strong shaking (MMI VII) occurred over a 40 km wide region near the epicenter that includes the city of Ridgecrest. Shaking was widely felt throughout California, including light to moderate ground shaking in Los Angeles, weak shaking in the San Francisco Bay Area, and felt shaking extending at least as far east as Phoenix and as far north as Sacramento.

Largest Events

  • 04 Jul 2019 10:33:48 PDT, (35.705, -117.508), depth 8.7km, 12km SW of Searles Valley, California
  • 05 Jul 2019 20:19:52 PDT, (35.766, -117.605), depth 10km, 17km NNE of Ridgecrest, California

Aftershocks

Aftershocks are occurring over a 50 km wide area, with a cluster of activity approximately 25 km NW from the mainshock about 10 km to the SE of the Coso Geothermal Field.

  • As of 05 Jul 2019, 04:00PM PDT, there have been nearly 3,000 aftershocks recorded in the full sequence. This significantly underestimates the total number of aftershocks as the processing system is saturated with data and smaller events in particular are not yet identified.
  • Number ≥ M7: 1
  • Number ≥ M6: 1
  • Number ≥ M5: 9
  • Number ≥ M4: 59
  • Number ≥ M3: 400
  • Aftershocks are expected to continue for months to years, but the magnitude and number will decrease through time. The largest expected is approximately 1 magnitude unit smaller than the mainshock.
  • There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.

Possible Foreshocks

  • There were 9 events during the 3 days prior to the earthquake (within a 10 km radius).
  • The largest was M4.0 (2019/07/04, about 30 minutes prior to the M6.4).
Map showing relocated current events in the Ridgecrest earthquake sequence. Events are shown size-scaled by magnitude. Figure from E. Hauksson.
Time series of the Ridgecrest earthquake sequence. The upper plot shows the cumulative number of events (blue), as well as the number of earthquakes per 20 minutes (green). The lower plot shows earthquake magnitudes through time, with events of M≥4 marked as red stars.

Historical Seismicity

  • Since our records began in 1932 we’ve had 31 events of M4 or greater within 10km of today’s event.
  • The largest historic event was M5.8 on 1995/09/20.
  • The most recent historic event was M4.1 on 01 Nov 2011.

Faults

The M6.4 earthquake on 7/4/2019 appears to have broken across two faults in the Airport Lake Fault Zone. The M7.1 earthquake on 7/5/2019 appears to be on the same fault zone, and has a right-lateral strike-slip mechanism. The M7.1 epicenter is located at the NW end of NW-oriented fault involved in the M6.4 earthquake. Surface rupture had been identified from both the July 4 M6.4 and July 5 M7.1 events. For an earthquake this large, surface rupture is expected. Field teams in the Ridgecrest area are now working on documenting fault offsets in the field.

Tectonic Summary

The July 4th, 2019 Mw 6.4 earthquake in eastern California, southwest of Searles Valley, occurred as the result of shallow strike slip faulting in the crust of the North America plate. Focal mechanism solutions for the earthquake indicate rupture occurred on a steeply dipping fault as the result of either right lateral slip on a plane striking NW-SE, or as left lateral slip on a plane striking SW-NE. At the location of this earthquake, approximately 150 km northeast of San Andreas Fault – the major plate boundary in the region – the Pacific plate moves to the northwest with respect to the North America plate at a rate of approximately 48 mm/yr. The location of the earthquake falls within the Eastern California shear zone, a region of distributed faulting associated with motion across the Pacific:North America plate boundary. More detailed studies will be required to precisely identify the causative fault associated with this event.

This region of eastern California has hosted numerous moderate sized earthquakes. Over the past 40 years, 8 other M5+ earthquakes have occurred within 50 km of the July 4th, 2019 earthquake. The largest of these was a M5.8 event on September 20, 1995, about 13 km to the west-northwest of today’s event, which was felt strongly in the China Lake-Ridgecrest area, and more broadly from Los Angeles to Las Vegas. As of 1 hour after the event the July 4th, 2019 earthquake has been followed by numerous aftershocks, the largest of which was a M 4.7 earthquake 2 minutes after the M 6.4 event. Most aftershocks align in a SW-NE trend around the M 6.4 earthquake. The M 6.4 event was also preceded by a series of very small earthquakes over the previous hour, including a M 4.0 event about 30 mins earlier.

Additional Information


Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

Probability: The probability in percent the earthquake is associated with this fault.

SCSN: Caltech/USGS Southern California Seismic Network

**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

This information is subject to change as more up-to-date data become available.

]]>
../../index.php/2019/07/04/07-2019-ridgecrest-sequence/feed/ 0
06/12/2019, M3.7 near Camarillo ../../index.php/2019/06/13/06-12-2019-m3-7-near-camarillo/ ../../index.php/2019/06/13/06-12-2019-m3-7-near-camarillo/#respond Thu, 13 Jun 2019 01:02:49 +0000 http://www.scsn.org/?p=3422 ]]> Event

  • 12 Jun 2019 17:07:33 PDT, (34.073, -119.040), depth 18.5km.
  • 16km S of Camarillo, California

Aftershocks

  • As of 12 Jun 2019, 05:59PM PDT, there have been no aftershocks recorded.
  • Aftershocks may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock.
  • There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.

Historical Seismicity

  • Since our records began in 1932 we’ve had 7 events of M4 or greater within 10km of today’s event.
  • The largest historic event was M5.3 on 1973/02/21.
  • The most recent historic event was M4.4 on 02 May 2009.

Faults

  • CFM fault associations: most likely Anacapa; Dume fault segment (40%). Alternates: Not associated with a CFM modeled fault (24%), Other CFM faults (36%).*
  • Nearby faults: Sycamore Canyon fault (2.6 km), Malibu Coast fault zone (Malibu Coast fault) (2.7 km), Boney Mountain fault (4.7 km) and Anacapa-Dume fault (8.3 km).**

Additional Information




*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

Probability: The probability in percent the earthquake is associated with this fault.

SCSN: Caltech/USGS Southern California Seismic Network

**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

This information is subject to change as more up-to-date data become available.

]]>
../../index.php/2019/06/13/06-12-2019-m3-7-near-camarillo/feed/ 0
06/05/2019, Pair of M4.3 near San Clemente Is ../../index.php/2019/06/05/06-05-2019-m4-3-near-san-clemente-is/ ../../index.php/2019/06/05/06-05-2019-m4-3-near-san-clemente-is/#respond Wed, 05 Jun 2019 13:35:25 +0000 http://www.scsn.org/?p=3403 ]]> Events

  • 05 Jun 2019 03:47:18 PDT, (32.812, -118.492), depth 7.8km, 14km W of San Clemente Is.
  • 05 Jun 2019 07:32:09 PDT, (32.813, -118.532), depth 7.8km, 17km W of San Clemente Is.

Aftershocks

  • As of 07 Jun 2019, 00:00AM PDT, there have been 7 aftershocks recorded. The largest was M3.5 (smallest M2.3).
  • Aftershocks may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock.
  • There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.

Historical Seismicity

  • Since our records began in 1932 we’ve had 4 events of M4 or greater within 10km of today’s event.
  • The largest historic event was M4.6 on 1952/02/13.
  • The most recent historic event was M4.1 on 10 Nov 2014.

Faults

  • Nearby faults: San Clemente fault zone (San Clemente fault) (11.9 km).**

Additional Information


Below are the waveform data associated with these events, as recorded in our Live Seismograms Feed. Note that the closest station to the epicenter captured in this stream is Long Beach CI.RPV at approximately 104km away.


**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

This information is subject to change as more up-to-date data become available.

]]>
../../index.php/2019/06/05/06-05-2019-m4-3-near-san-clemente-is/feed/ 0
Glen Avon Earthquake Swarm 5/25/2019- ../../index.php/2019/06/03/glen-avon-earthquake-swarm-5-25-2019/ ../../index.php/2019/06/03/glen-avon-earthquake-swarm-5-25-2019/#respond Mon, 03 Jun 2019 15:21:56 +0000 http://www.scsn.org/?p=3382 ]]> We are actively updating this post with information…

Summary

Swarms of small magnitude events are relatively common in this area, extending from Riverside to Chino. Based on past historic recordings this swarm is only expected to generate events of magnitude less than 4.0. The swarm falls within the northeast trending Fontana Seismicity Trend, which has no major mapped fault but relatively abundant small seismicity indicating a local network of small fractures and faults. Earthquakes in this area are probably related to the tectonic loading of the nearby San Jacinto and San Andreas faults.

Events

  • Current swarm started 2019/05/25 and SCSN has recorded over 1,180 events so far (2019/07/02 4:30pm).
  • Largest event so far: M3.2, 02 Jun 2019 16:36:36 PDT, 5km NNW of Glen Avon, California (34.053, -117.500), depth 2.5km.
  • Number of events M2-M3: 53 (as of 2019/07/02 4:30pm)
  • Number of events M≥3: 5 (as of 2019/07/02 4:30pm)
    • M3.1 01 Jun 2019 19:19:48 PDT
    • M3.2 02 Jun 2019 16:36:36 PDT
    • M3.2 05 Jun 2019 17:20:57 PDT
    • M3.0 13 Jun 2019 19:16:07 PDT
    • M3.0 16 Jun 2019 17:12:01 PDT
    Time series of the current (May/June 2019) earthquake swarm in the Fontana/Glen Avon area. The upper plot shows the cumulative number of events (blue), as well as the number of earthquakes per 4 hours (green), between 25 May 2019 and 2 July 2019. The lower plot shows earthquake magnitudes through time, with events of M≥3 marked as red stars.
  • Events are relatively shallow for southern California, contributing to several of them being felt.
  • Earthquake swarms are characterised as clusters of events in space and time that have no obvious mainshock. See this page for further information on southern California swarms.

Historical Seismicity

  • Previous swarms in this area: swarms in this area have been recorded back through the 1980s, when our instrumentation network became sensitive enough to detect these smaller events. Swarms containing fewer events (between 50 and 100) were recorded in February and March 2019 along the same fracture, slightly to the NE.
  • Since our records began in 1932 we’ve had 18 events of M4 or greater within 10km of today’s event. Most of these events above M4 lie on or near the major adjacent faults: the San Jacinto and San Andreas.
Map of seismicity in the Fontana/Glen Avon area. Red circles show events in the current (May/June 2019) swarm. Blue stars show historic earthquakes of M4 or above. Black dots show historic seismicity of all magnitudes. Fault traces are shown in pink.

Faults

  • CFM fault associations: most likely Fontana Seismicity lineament (89.9%). Alternates: Not associated with a CFM modeled fault (10.1%).*
  • Nearby faults: Red Hill-Etiwanda Avenue fault (10.7 km), Red Hill-Etiwanda Avenue fault (Etiwanda Avenue fault) (10.9 km), Sierra Madre fault zone, Cucamonga section (Cucamonga fault) (11.9 km) and San Jacinto fault zone, San Bernardino section (San Jacinto fault) (15.4 km).**

Additional Information


Below is a video depicting the emergence of the 2019 Glen Avon earthquake swarm through time from May 19, 2019 through to June 6, 2019. Markers are scaled to depict relative magnitude.

Click on Glen Avon KMZ to download the .kmz and run this visualization yourself in Google Earth. (Unzip the file and drag/import it into an open Google Earth window.) Earthquakes included are scaled based on magnitude and are clickable to display a tooltip with the date, magnitude, location, and depth of each earthquake. The data displayed can be acquired at scedc.caltech.edu.

Below are the waveform data associated with this swarm, as recorded in our Live Seismograms Feed for events of magnitude 3.0 and higher. Note that for some of the events, small foreshocks can be seen shortly before the main events listed in the title.

*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

Probability: The probability in percent the earthquake is associated with this fault.

SCSN: Caltech/USGS Southern California Seismic Network

**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

This information is subject to change as more up-to-date data become available.

]]>
../../index.php/2019/06/03/glen-avon-earthquake-swarm-5-25-2019/feed/ 0
05/08/2019, M3.5 near Ocotillo Wells ../../index.php/2019/05/08/05-08-2019-m3-5-near-ocotillo-wells/ ../../index.php/2019/05/08/05-08-2019-m3-5-near-ocotillo-wells/#respond Wed, 08 May 2019 20:53:33 +0000 http://www.scsn.org/?p=3154 ]]> Event

  • 08 May 2019 09:14:59 PDT, (33.213, -116.067), depth 10.6km.
  • 10km NE of Ocotillo Wells, California

Aftershocks

  • As of 17 May 2019, 12:08PM PDT, there have been 11 aftershocks recorded.
  • The largest was M1.3 (smallest M0.8).
  • More aftershocks may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock.
  • There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.

Possible Foreshocks

  • There were 4 events during the 3 days prior to the earthquake (within a 10 km radius).
  • The largest was M1.7 (2019/05/06).

Historical Seismicity

  • Since our records began in 1932 we’ve had 55 events of M4 or greater within 10km of today’s event.
  • The largest historic event was M6.6 on 1968/04/09.
  • The most recent historic event was M4.3 on 09 Feb 2007.

Faults

  • CFM fault associations: most likely Clark fault; south segment (87.6%). Alternates: Not associated with a CFM modeled fault (4.1%), Other CFM faults (8.3%).*
  • Nearby faults: San Jacinto fault zone, Borrego Mountain section (Coyote Creek fault) (8.7 km), San Jacinto fault zone, Anza section (Clark fault) (10.1 km) and San Jacinto fault zone, Coyote Creek section (Coyote Creek fault) (12.5 km).**

Additional Information


Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.


*Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

Probability: The probability in percent the earthquake is associated with this fault.

SCSN: Caltech/USGS Southern California Seismic Network

**U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

This information is subject to change as more up-to-date data become available.

]]>
../../index.php/2019/05/08/05-08-2019-m3-5-near-ocotillo-wells/feed/ 0
04/22/2019, M3.7 near Imperial ../../index.php/2019/04/23/04-22-2019-m3-7-near-imperial/ ../../index.php/2019/04/23/04-22-2019-m3-7-near-imperial/#respond Tue, 23 Apr 2019 05:05:07 +0000 http://www.scsn.org/?p=3111 ]]>
  • 22 Apr 2019 20:24:03 PDT, (32.903, -115.512), depth 17.0km, 8km NE of Imperial, California
  • Aftershocks: so far (17 May 2019, 08:37AM PDT) there have been 46 aftershocks recorded, the largest M2.9 (smallest M1.0). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • There were 4 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was M2.2 (2019/04/23).
  • Historical seismicity: since our records began in 1932 we’ve had 92 events of M4 or greater within 10km of today’s event, the largest was M6.9 (1940/05/19) and the most recent was M4.2 on 28 Aug 2012.
  • CFM fault associations: most likely Imperial fault; Edip segment (28.9%). Alternates: Not associated with a CFM modeled fault (19.7%), Other CFM faults (51.4%).*
  • Nearby faults: Imperial fault (2.7 km), Brawley seismic zone (Brawley fault zone) (3.0 km), Brawley seismic zone (4.2 km), San Jacinto fault zone, Superstition Hills section (Wienert fault) (12.3 km), San Jacinto fault zone, Superstition Hills section (Superstition Hills flt) (13.9 km) and Brawley seismic zone (Rico fault) (14.7 km).**
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

    *Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

    CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

    Probability: The probability in percent the earthquake is associated with this fault.

    SCSN: Caltech/USGS Southern California Seismic Network

    **U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

    This information is subject to change as more up-to-date data become available.

    ]]>
    ../../index.php/2019/04/23/04-22-2019-m3-7-near-imperial/feed/ 0
    04/03/2019, M3.6 near Yorba Linda ../../index.php/2019/04/03/04-03-2019-m3-6-near-yorba-linda/ ../../index.php/2019/04/03/04-03-2019-m3-6-near-yorba-linda/#respond Wed, 03 Apr 2019 15:33:04 +0000 http://www.scsn.org/?p=3092 ]]>
  • 03 Apr 2019 05:06:22 PDT, (33.867, -117.728), depth 4.8km, 8km ESE of Yorba Linda, California
  • Aftershocks: so far (17 May 2019, 08:40AM PDT) there have been 26 aftershocks recorded, the largest M2.6 (smallest M0.9). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • There were 1 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was M1.2 (2019/04/02).
  • Historical seismicity: since our records began in 1932 we’ve had 13 events of M4 or greater within 10km of today’s event, the largest was M5.4 (2008/07/29) and the most recent was M4.1 on 29 Mar 2014.
  • CFM fault associations: most likely Peralta Hills fault (63.9%). Alternates: Not associated with a CFM modeled fault (8.2%), Other CFM faults (27.9%).*
  • Nearby faults: Elsinore fault zone, Whittier section (Whittier fault) (1.5 km), Peralta Hills fault (5.0 km), El Modeno fault (7.7 km), Elsinore fault zone, Chino section (Chino fault) (8.0 km), Elsinore fault zone, Glen Ivy section (Tin Mine fault) (8.2 km), Elsinore fault zone, Glen Ivy section (Main Street fault) (11.1 km) and Elsinore fault zone, Glen Ivy section (Glen Ivy North fault) (13.4 km).**
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

    *Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

    CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

    Probability: The probability in percent the earthquake is associated with this fault.

    SCSN: Caltech/USGS Southern California Seismic Network

    **U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

    This information is subject to change as more up-to-date data become available.

    ]]>
    ../../index.php/2019/04/03/04-03-2019-m3-6-near-yorba-linda/feed/ 0
    02/07/2019, M4.0 near Ludlow ../../index.php/2019/02/07/02-07-2019-m4-0-near-ludlow/ ../../index.php/2019/02/07/02-07-2019-m4-0-near-ludlow/#respond Thu, 07 Feb 2019 22:36:44 +0000 http://www.scsn.org/?p=3064 ]]>
  • 07 Feb 2019 08:41:24 PDT, (34.703, -116.287), depth 1.6km, 12km W of Ludlow, California
  • Aftershocks: so far (17 May 2019, 08:43AM PDT) there have been 81 aftershocks recorded, the largest M4.0 (smallest M0.4). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • There were 13 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was M3.2 (2019/02/07).
  • Historical seismicity: since our records began in 1932 we’ve had 62 events of M4 or greater within 10km of today’s event, the largest was M7.1 (1999/10/16) and the most recent was M4.1 on 23 Feb 2016.
  • CFM fault associations: most likely Hector Mine rupture dipping (91.6%). Alternates: Not associated with a CFM modeled fault (7.9%), Other CFM faults (0.5%).*
  • Nearby faults: Unnamed fault east of Pisgah (5.1 km), Lavic Lake fault zone (Lavic Lake fault) (5.8 km), Pisgah-Bullion fault zone, Pisgah section (Pisgah fault) (9.8 km), Lavic Lake fault zone (10.5 km), Ludlow fault (11.1 km) and Pisgah-Bullion fault zone, Bullion section (Bullion fault) (12.9 km).**
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • *Earthquakes can occur both near or on major known faults, and in places where no clear fault zones are known. Using the statistical method of Evans et al. (in prep. 2019) the location and focal mechanism of this earthquake suggest the above association with modeled faults in the Community Fault Model (CFM) provided by the Southern California Earthquake Center (SCEC) and Harvard University. Note that the CFM fault association may be different from the nearby faults list. Differences may arise due to different fault databases, and because the CFM fault association uses the hypocenter with relation to subsurface 3-dimensional fault orientation models, while the nearby faults list utilizes mapped surface traces as they relate to the epicenter.

    CFM Fault: SCEC CFM 5.0 Fault name and closest segment if available; The CFM is maintained by Harvard University, Dept of Earth & Planetary Sciences.

    Probability: The probability in percent the earthquake is associated with this fault.

    SCSN: Caltech/USGS Southern California Seismic Network

    **U.S. Geological Survey and California Geological Survey, 2006, Quaternary fault and fold database for the United States, accessed 2015, from USGS web site: https://earthquake.usgs.gov/hazards/qfaults/

    This information is subject to change as more up-to-date data become available.

    ]]>
    ../../index.php/2019/02/07/02-07-2019-m4-0-near-ludlow/feed/ 0
    01/29/2019, M3.6 near Lucerne Valley ../../index.php/2019/01/30/01-29-2019-m3-6-near-lucerne-valley/ ../../index.php/2019/01/30/01-29-2019-m3-6-near-lucerne-valley/#respond Wed, 30 Jan 2019 02:51:34 +0000 http://www.scsn.org/?p=3061 ]]>
  • 29 Jan 2019 18:40:12 PST, (34.408, -116.892), depth -0.5km, 8km ESE of Lucerne Valley, California
  • Aftershocks: so far there have been no aftershocks recorded. Some may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • Historical seismicity: since our records began in 1932 we’ve had 53 events of M4 or greater within 10km of today’s event, the largest was M5.3 (1992/11/27) and the most recent was M4.6 on 05 Jul 2014.
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • ]]>
    ../../index.php/2019/01/30/01-29-2019-m3-6-near-lucerne-valley/feed/ 0
    01/22/2019, M3.6 near Brawley ../../index.php/2019/01/23/01-22-2019-m3-6-near-brawley/ ../../index.php/2019/01/23/01-22-2019-m3-6-near-brawley/#respond Wed, 23 Jan 2019 21:27:35 +0000 http://www.scsn.org/?p=3060 ]]>
  • 22 Jan 2019 00:24:44 PST, (32.947, -115.515), depth 15.4km, 4km SSE of Brawley, California
  • Aftershocks: so far (23 Jan 2019, 01:22PM PST) there have been 12 aftershocks recorded, the largest M2.7 (smallest M1.1). More may be expected in the next few days, the largest expected is approximately 1 magnitude unit smaller than the mainshock. There is a small chance (about 5%) that a larger quake could occur, with the likelihood decreasing over time.
  • There were 1 events during the 3 days prior to the earthquake (within a 10 km radius), the largest was M3.1 (2019/01/22).
  • Historical seismicity: since our records began in 1932 we’ve had 93 events of M4 or greater within 10km of today’s event, the largest was M6.9 (1940/05/19) and the most recent was M4.2 on 28 Aug 2012.
  • Links for: USGS earthquake page, ShakeMap, DYFI, waveforms.
  • Visit our special reports page for further information on local notable earthquakes.
  • Below are the waveform data associated with this event, as recorded in our Live Seismograms Feed.

    ]]>
    ../../index.php/2019/01/23/01-22-2019-m3-6-near-brawley/feed/ 0